Musnad Ahmad 30:749

Zayd ibn al-Hubab narrated to us, Husayn ibn Waqid narrated to me, Muhammad ibn Ziyad narrated to me, that Abu Hurayrah narrated to him, he said: The Messenger of Allah, may Allah bless him and grant him peace, said: "The upper hand is better than the lower hand, and begin with those whom you support."